Formaldehyde-based resins or formaldehyde-containing resins, such as urea-formaldehyde (UF) resins, phenol-formaldehyde (PF) resins, including PF resins extended with urea (PFU) and melamine-formaldehyde (MF) resins find widespread use as adhesives and bonding agents for making a wide variety of products.
For example, PF and PUF resins in particular have been the mainstays of fiberglass insulation binder technology over the past several years. Such resins are inexpensive and provide cured fiberglass insulation products with excellent physical properties.
Fiberglass insulation, used generally in an uncompressed mat or blanket form, provides heat insulation for roof and wall structures in residential and commercial buildings, and is used in a compressed form as insulation for pipes and other conduits, and also is used in a variety of other molded forms.
Such fiberglass insulation products are easy to install and provide an economical and effective insulating barrier to reduce heat loss through the roof and wall structures of buildings and through the surface of pipes and other conduits or containers used to contain hot or cold fluids and other materials.
Fiberglass insulation mats and blankets often are shipped in a compressed, rolled form to facilitate transportation and reduce costs. When such compressed bundles of fiberglass are used at a job site, it is important that the compressed fiberglass product recover a substantial amount of it pre-compressed thickness. If not, the product will suffer a decrease is its thermal insulation and sound attenuation properties. Fiberglass insulation made with PF and PFU resins is able to recover most of its pre-compressed thickness, thus contributing to the wide acceptance of these resins as binders in this application.
The ability of these formaldehyde-based resins to provide the necessary performance benefits at a reduced cost relative to other adhesive technologies has thus made formaldehyde-based resins, including UF, PF and PUF resins, popular in a variety of products that find their way into commercial and residential uses.
One of the drawbacks of using these resins, both for making insulation and for other consumer products, however, is the potential for formaldehyde emissions from the finished article. It has long been observed that gaseous formaldehyde is released from such articles, some of which is attributable to unreacted formaldehyde in the cured resin binder and some of which is attributable to degradation or decomposition products generated over time under acidic conditions, elevated temperatures, and/or high humidity.
Thus, there is a continuing need for new methods for reducing formaldehyde emission in products produced using formaldehyde-based or formaldehyde-containing resins.
One of the common forms of conventional fiberglass insulation is an elongated mat or blanket of uniform width and thickness, having a backing sheet, possibly of a vapor impervious material, adhesively secured to one side surface of the mat or blanket. This mat or blanket often is formed in a continuous process by compressing the fiberglass mat or blanket against an adhesively coated surface of the backing sheet material. Such a method is an economical and an efficient means of forming a conventional fiberglass insulation product that is easy to handle and install. The present invention takes advantage of this conventional product configuration to produce fiberglass insulation products having a reduced tendency to emit formaldehyde into the environment.